1. Field of the Invention
The present invention relates to an optical information recording medium that is preferably used as an optical information recording medium in which, for example, information is recorded using light beams and is reproduced using the light beams.
2. Description of the Related Art
Heretofore, as an optical information recording medium, a disc-shaped optical information recording medium has been widely used, and in general, a compact disc (CD), a digital versatile disc (DVD), a Blu-ray disc (registered trademark, hereinafter referred to as “BD”), and the like have been used.
In addition, an optical information recording/reproducing device using the optical information recording medium described above is designed so as to record various types of information, such as various types of contents including music contents and image contents or various types of data for computers, in the optical information recording medium. In particular, recently, since the amount of information has been increased due to, for example, a higher degree of image fineness and a higher degree of sound quality, and in addition, since an increase in the number of contents to be recorded in one optical information recording medium has been requested, the optical information recording medium is further desired to have a larger recording capacity.
Accordingly, as one method for increasing the capacity of an optical information recording medium, an optical information recording medium has been proposed in which microscopic holograms formed by interfering light beams of two systems are used as recording marks and are overlapped with each other in the thickness direction of the optical information recording medium so as to record information in one recording layer which corresponds to that recorded in a plurality of layers (for example, see Japanese Patent Application Laid-Open No. 2008-71433).